Log4j2 SyslogAppender 不工作

Question

我正在使用 Log4j 2.1 版（最新的稳定版本）并尝试使用 Syslog appender 登录到 syslog 服务器。我正在使用他们官方网站上给出的配置（http://logging.apache.org/log4j/2.x/manual/appenders.html#SyslogAppender）：

<Syslog name="RFC5424" format="RFC5424" host="localhost" port="514"
        protocol="UDP" appName="MyApp" includeMDC="true"
        facility="LOCAL0" enterpriseNumber="18060" newLine="true"
        messageId="Audit" id="App"/>

当我启动我的应用并执行 LogManager.getLogger() 时，我收到一个错误（堆栈跟踪如下），所以，在我向他们的错误跟踪器报告错误之前，我做错了什么吗？

014-11-17 18:26:23,640 ERROR Unable to invoke factory method in class class org.apache.logging.log4j.core.appender.SyslogAppender for element Syslog. java.lang.reflect.InvocationTargetException
  at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
  at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:606)
  at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.build(PluginBuilder.java:135)
  at org.apache.logging.log4j.core.config.AbstractConfiguration.createPluginObject(AbstractConfiguration.java:766)
  at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:706)
  at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:698)
  at org.apache.logging.log4j.core.config.AbstractConfiguration.doConfigure(AbstractConfiguration.java:358)
  at org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:161)
  at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:359)
  at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:420)
  at org.apache.logging.log4j.core.LoggerContext.start(LoggerContext.java:138)
  at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:147)
  at org.apache.logging.log4j.core.impl.Log4jContextFactory.getContext(Log4jContextFactory.java:41)
  at org.apache.logging.log4j.LogManager.getContext(LogManager.java:175)
  at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:426)
  at org.apache.logging.log4j.LogManager.getLogger(LogManager.java:408)
  at Log.<clinit>(Log.java:7)
Caused by: java.lang.IllegalArgumentException: No structured id name was supplied
  at org.apache.logging.log4j.message.StructuredDataId.<init>(StructuredDataId.java:92)
  at org.apache.logging.log4j.core.layout.Rfc5424Layout.<init>(Rfc5424Layout.java:139)
  at org.apache.logging.log4j.core.layout.Rfc5424Layout.createLayout(Rfc5424Layout.java:657)
  at org.apache.logging.log4j.core.appender.SyslogAppender.createAppender(SyslogAppender.java:133)
... 19 more

Answer 1

您需要包含mdcId 属性。例如：

<Syslog name="RFC5424" format="RFC5424" host="localhost" port="514"
        protocol="UDP" appName="MyApp" mdcId="mdc" includeMDC="true"
        facility="LOCAL0" enterpriseNumber="18060" newLine="true"
        messageId="Audit" id="App"/>